The class of polymers of carbon monoxide and olefin(s) has been known for some time. Brubaker, U.S. Pat. No. 2,495,286, produced such polymers of relatively low carbon monoxide content in the presence of free radical initiators, e.g., peroxy compounds. U.K. 1,081,304 produces similar polymers of higher carbon monoxide content in the presence of alkylphosphine complexes of palladium as catalyst. Nozaki extended the process to produce linear alternating polymers through the use of arylphosphine complexes of palladium and certain inert solvents, e.g., U.S. Pat. No. 3,694,412.
More recently the class of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon has become of greater interest in part because of the greater availability of the polymers. The more recent general process for the production of the polymers is illustrated by Published European Patent Applications 121,965, 181,014, 222,454 and 257,663 among others. The process generally involves the use of a catalyst system formed from a compound of a Group VIII metal selected from palladium, cobalt or nickel, the anion of a non-hydrohalogenic acid having a pKa below about 6 and a bidentate ligand of phosphorous, arsenic or antimony.
The resulting polymers are relatively high molecular weight materials having utility as premium thermoplastics in the production of shaped articles such as containers for food and drink and as parts and housings for the automotive industry. Although the polymers are relatively stable, the linear alternating polymers do undergo to some degree the degradation upon exposure to elevated temperature which is characteristic of most if not all organic polymers.
Russell et al, U.S. Pat. No. 3,929,729 and U.S. Pat. No. 4,024,104, teach the use of certain benzoquinones and of certain benzotriazoles as thermal stabilizers for certain polymers of carbon monoxide and ethylene with optional third monomers, but the polymers tested are limited and the disclosure does not appear to be directed solely towards linear alternating polymers. In fact, a number of conventional thermal stabilizers that are usefully employed with one or more other premium thermoplastics do not appear to effectively stabilize the linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon. It would be of advantage to provide for efficient stabilization of such polymers against thermal degradation.